Controversial Midland MP Tom Watson claims he has new evidence about historic allegations of child abuse which police have overlooked.

The West Midland MP whose resignation helped plunge Labour into crisis has insisted he has no regrets – and is looking forward to life on the backbenches.

Tom Watson (Lab West Bromwich East) plans to rededicate himself to the campaigns which made him a household name, targeting unethical behaviour in parts of the media.

He quit as Labour’s deputy chairman and campaigns co-ordinator in the wake of a simmering row over the role of trade unions in selecting Labour candidates.

The MP believes he has been neglecting the inquiry he launched into historic allegations of child abuse – despite receiving testimony from survivors of abuse who were speaking out for the first time.

“It started with a single email from a retired child protection officer in the Midlands, who said they tried to get this investigated back in the early 90s. Everyone ignored them.

“Jimmy Saville happened and they said ‘you’re the guy who took on Murdoch and so we think you might be able to help us’.

“I looked at this email and thought, ‘if I reply to this it’s probably another two years of my life taken up’.”

The inquiry really took off when he raised it in the House of Commons, he said. “It led to an explosion where we had about 300 separate allegations made through my team, not all of them valid – the majority just repeating rumours they had read on the internet – but within that pile there were survivors of sexual abuse who have spoken out for the first time.

“And I think a couple of those could be significant witnesses if the police inquiry proceeds in the way it’s going. There’s a lot to do on that and I feel duty bound to do it, because when you meet some of these survivors they are very vulnerable people.

“That had been playing on my mind. There’s that nagging doubt that I’ve unleashed this inquiry but not given it the attention it deserves. I’m very much looking forward to reallocating time to that bit of it.”

The front-bench role he held since 2011 – which had taken a toll on his health, he said.